Receivers often have a DC offset with respect to a receiver input signal such that the actual voltage of the signal becomes offset from its ideal voltage. The DC offset may be introduced into the signal prior to its being input to the receiver, within the receiver itself, or in a combination of these. This effect can reduce the performance of the receiver.
In systems such as 100 Mb/s and Gigabit Ethernet and the like, conventional receivers typically address DC offset correction using a combination of analog and digital circuitry. The electrical signaling in these systems is such that there is a continuous non-static waveform at the receiver input. Thus, there is no time period during which the receiver input signal remains at a nominal voltage level. In addition, the signal voltage levels are usually such that the output of an analog-to-digital converter (ADC) in the receiver does not use the entire range of the ADC. Thus, conventional DC offset correction is unsuitable for systems such as 10 Mb/s Ethernet receivers because it is not possible to determine an accurate offset based on maximal- and minimal-valued ADC outputs.
Before undertaking the DETAILED DESCRIPTION OF THE INVENTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or,” is inclusive, meaning and/or; the term “each” means every one of at least a subset of the identified items; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term “controller” means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior as well as future uses of such defined words and phrases.